Change default line width for Ink Annotations

Q: How do I change the default line width for Ink Annotations?

A: This can be done by using annotation presets:

const myAnnotationPresets = instance.annotationPresets
myAnnotationPresets['ink'] = {
 lineWidth: 3,

or (if you want to preserve the other values for the ink annotation):

myAnnotationPresets['ink'] = Object.assign({},, {
  lineWidth: 3

After this is run, if the user clicks in the Ink tool button, the line width will be set to 3, the new default until the value is changed.